Water hammer protection device suitable for silt-containing water flow pipeline and test system

Abstract

The invention discloses a water hammer protection device suitable for a silt-containing water flow pipeline and a test system, and relates to the field of water hammer protection, the water hammer protection device suitable for the silt-containing water flow pipeline comprises at least one pressure reduction short branch pipe arranged along a water delivery main pipe, and one end of the pressure reduction short branch pipe is communicated with the water delivery main pipe; the spring control valve is arranged at the other end in the pressure reduction short branch pipe; and when a water hammer effect occurs in the water delivery main pipe, overpressure water flow flows out from the end part of the pressure reduction short branch pipe through the spring control valve. A plurality of water hammer protection devices are arranged on the upstream pipeline of the valve at the tail end of the main pipeline at intervals, and when the valve at the tail end of the pipeline breaks down to be closed or is regularly closed to cause water hammers in the pipeline, spring control valves on the water hammer protection devices are automatically compressed to discharge part of overpressure water flow in the pipeline out of the pipeline in time through an outflow bottom plate; the thickness of the pipe wall of the water hammer generation section can be effectively reduced, and the water hammer protection device is low in manufacturing cost and convenient to maintain.

Description

Technical Field

[0001] The invention relates to the technical field of water hammer protection, in particular to a water hammer protection device and a test system suitable for a sediment-containing water flow pipeline. Background Art

[0002] The current status of water resources in my country is that precipitation in the north and south is unbalanced, and there is a big difference in available water resources. In the context of implementing the rational allocation, development and utilization of water resources in the basin, pipeline water supply has become the first choice for cross-regional water transmission, balanced water resource distribution, and achieving river connection in the basin. Long-distance water transmission pipelines have many pipe connection interfaces, large pipeline fluctuations, and many hydraulic components. When the flow rate in the pipe suddenly changes, the pressure in the pipe suddenly changes, causing water hammer phenomenon. Accidents such as pipe bursts or suction and collapse will occur at vulnerable locations of the pipeline system, causing serious economic losses and engineering accidents. Arranging traditional water hammer protection equipment such as air valves, water hammer relief valves, air tanks, and pressure regulating towers in the pipeline to protect the pipeline from water hammer can effectively avoid the occurrence of water hammer accidents.

[0003] The protective effect of traditional protective equipment is obvious, but the investment in protective equipment will increase significantly with the increase of pipe diameter and water hammer pressure of the protected pipe. In addition, during the flood season of sediment-rich rivers, the flow rate of river water increases and the sediment content increases. Even if it passes through reservoirs or sedimentation tanks, some sediment will still enter the pressurized water pipeline. If water hammer occurs in a pipeline containing sediment, the sediment particles will not only significantly affect the water hammer pressure value, but also cause structural damage to the protective equipment on the water supply system, resulting in operational failure of the protective equipment, affecting the safe and stable operation of the water supply system and increasing the later operation and maintenance costs of the project.

[0004] The present invention provides a new solution for pipeline water hammer protection, and is of great significance for reducing the investment in pipeline water hammer protection and protecting pipeline water hammer in areas with a lot of sediment. Summary of the invention

[0005] In view of the above problems existing in the prior art, the present invention is proposed.

[0006] Therefore, the problem to be solved by the present invention is that the cost of traditional protective equipment will increase significantly with the increase of pipeline water hammer pressure, and if pipeline water hammer occurs in a pipeline containing sediment water flow, the sediment particles will not only significantly affect the pipeline water hammer pressure value, but also cause structural damage to the protective equipment on the water supply system, resulting in operational failure of the protective equipment, affecting the safe and stable operation of the water supply system, and increasing the later operation and maintenance costs of the project.

[0007] To solve the above technical problems, in the first aspect, the present invention provides the following technical solutions: a water hammer protection device suitable for a silt-containing water flow pipeline, comprising a pressure reducing short branch pipe, at least one of which is arranged along a water supply main pipe and one end of which is connected to the water supply main pipe; a spring control valve, which is arranged at the other end of the pressure reducing short branch pipe; when a water hammer effect occurs in the water supply main pipe, the overpressure water flow will flow out from the end of the pressure reducing short branch pipe through the spring control valve.

[0008] As a preferred solution of the water hammer protection device suitable for a silt-containing water flow pipeline described in the present invention, the pressure reducing short branch pipe is connected to the water supply main pipe through a three-way joint.

[0009] As a preferred solution of the water hammer protection device suitable for sediment-containing water pipelines described in the present invention, the diameter of the pressure reducing short branch pipe is 1 / 5 to 1 / 3 of the diameter of the water transmission main pipe.

[0010] As a preferred solution of the water hammer protection device suitable for a silt-containing water flow pipeline described in the present invention, the spring control valve includes an outflow bottom plate, a spring and a waterproof plug, and the outflow bottom plate and the waterproof plug are respectively fixedly arranged at both ends of the spring and the three are coaxial.

[0011] As a preferred solution of the water hammer protection device suitable for a sediment-containing water flow pipeline described in the present invention, at least one outflow hole is provided on the outflow bottom plate for connecting the pressure reducing short branch pipe with the outside.

[0012] As a preferred solution of the water hammer protection device suitable for sediment-containing water flow pipelines described in the present invention, the outflow bottom plate and the sides of the waterproof plug are fixedly provided with fixed steel sheets, and the two ends of the spring are respectively fixedly connected to the fixed steel sheets.

[0013] As a preferred solution of the water hammer protection device suitable for silt-containing water flow pipelines described in the present invention, a pull rope is also arranged between the outflow bottom plate and the waterproof plug, and the two ends of the pull rope are respectively fixedly connected to the outflow bottom plate and the waterproof plug.

[0014] As a preferred solution of the water hammer protection device suitable for a silt-containing water flow pipeline described in the present invention, the pull rope pre-applies tension to the spring so that the spring is compressed and pulled, and the pressure of the spring at this time is the same as the water pressure in the pressure reducing short branch pipe when no water hammer occurs.

[0015] On the other hand, the present invention also provides a water hammer protection test system, which includes the above-mentioned water hammer protection device, and also includes a pressure sensor, which is arranged upstream of the water hammer protection device and is used to measure the water pressure in the water supply main pipe; a water measuring weir, which is arranged at the water outlet of the water supply main pipe and is used to calibrate the flow of the water supply main pipe.

[0016] As a preferred solution of the water hammer protection test system of the present invention, the water measuring weir is a triangular water measuring weir, and a spherical stop valve is also provided at the water supply main pipe.

[0017] The beneficial effects of the present invention are as follows: the present invention arranges a plurality of water hammer protection devices at intervals in the upstream pipeline of the terminal valve of the main pipeline. When the terminal valve of the pipeline fails to close or closes regularly, causing water hammer in the pipe, the spring control valve on the water hammer protection device automatically compresses and discharges part of the overpressure water flow in the pipe through the outlet bottom plate in time out of the pipe. The relatively short distance before the terminal valve is concentratedly protected, the water hammer pressure in the pipe is quickly reduced, the time for the components in the pipeline to withstand the water hammer pressure shock is shortened, and the peak value of the water hammer pressure shock wave is reduced. The thickness of the pipe wall in the water hammer occurrence section can be effectively reduced, and the water hammer protection device is low in cost and easy to maintain. The invention can take into account both economic benefits and pipeline safety requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 This is the structural diagram of the water hammer protection device.

[0020] Figure 2 This is the structural diagram of the spring control valve.

[0021] Figure 3 This is a structural diagram of a spring-controlled valve with tension.

[0022] Figure 4 Schematic diagram of the application scenario of water hammer protection device.

[0023] Figure 5 Schematic diagram of the test system layout.

[0024] Figure 6 This is a schematic diagram of the pipeline layout of the QT project.

[0025] Figure 7 This is the pipeline flow velocity cloud diagram under each scheme when t=46.9s in Example 3.

[0026] Figure 8 This is the pipeline flow velocity cloud diagram under each scheme when t=93.8s in Example 3. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0028] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0029] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it an embodiment that is mutually exclusive with other embodiments, either individually or selectively.

[0030] Example 1

[0031] Reference Figure 1 to Figure 4 , which is the first embodiment of the present invention, provides a water hammer protection device suitable for a silt-containing water flow pipeline. The water hammer protection device suitable for a silt-containing water flow pipeline includes a pressure reducing short branch pipe 100 and a spring control valve 200.

[0032] Specifically, several pressure reducing short branch pipes 100 can be arranged upstream of the terminal control valve of the long-distance water transmission trunk line S, and the spacing between adjacent pressure reducing short branch pipes 100 can be determined in combination with the actual project. The pressure reducing short branch pipe 100 is connected to the water transmission trunk line S through a three-way joint 300.

[0033] The spring control valve 200 is arranged at the open end of the pressure reducing short branch pipe 100, and comprises an outflow bottom plate 201, a spring 202 and a waterproof plug 203. The outflow bottom plate 201 is fixedly connected to the flange at the open end of the pressure reducing short branch pipe 100.

[0034] Preferably, a fixed steel sheet 204 is fixed on the side wall of the flow bottom plate 201 and the waterproof plug 203, and the shape of the fixed steel sheet 204 is L-shaped. Both ends of the spring 202 are arranged through the fixed steel sheet 204 to ensure that the spring 204 rebounds after compression and resets the waterproof plug 203 without being ejected from the pressure reducing short branch pipe 100, thereby ensuring the structural stability of the spring-controlled valve 200.

[0035] Preferably, a water-stop rubber sheet may be arranged between the outflow bottom plate 201 of the spring control valve 200 and the flange of the pressure reducing short branch pipe 100 to make the water hammer protection device structure more rigorous and prevent the spring control valve 200 structure from leaking.

[0036] Preferably, Figure 3 As shown, a pull rope 205 is added between the waterproof plug 203 and the outflow bottom plate 201. The pull rope 205 is a high-toughness steel wire rope. The pull rope 205 is arranged along the central axis of the spring 202, and a tension is pre-applied to the spring 202. This tension compresses and pulls the spring 202, and its value is the same as the water pressure on the waterproof plug when no water hammer occurs, that is, when no water hammer occurs, the water pressure on one side of the waterproof plug 203 is balanced with the elastic force of the spring 202 on the other side;

[0037] When water hammer occurs, the water pressure on the waterproof plug is greater than the elastic force of the spring 202, the spring 202 is compressed, and the waterproof plug moves to the side of the spring 202, thereby reducing the water hammer pressure. When the water hammer wave disappears, the waterproof plug 203 returns to the initial position and maintains a balanced state. When the pipeline is in a waterless state, the spring 202 is pulled by the pull rope 205, which can prevent the waterproof plug 203 from being ejected by the spring 202.

[0038] Preferably, the diameter of the pressure reducing short branch pipe 100 is 1 / 5 to 1 / 3 of the diameter of the water supply main pipe S. The length of the pressure reducing short branch pipe 100 can be determined according to the total length of the spring control valve 200. For the safety and stability of the overall water supply system, the diameter and length of the pressure reducing short branch pipe 100 are required to be as small as possible while meeting the protection requirements.

[0039] The end control valve of the water main pipe S fails and closes, causing the pressure in the pipe to increase. When the pressure in the pipe is greater than the critical pressure value of the spring 202, the spring 202 deforms and compresses, and the high-pressure water in the pipe flows out from the outflow hole 201a of the outflow bottom plate 201 of the pressure reducing short branch pipe 100, thereby reducing the pressure in the water supply system pipe. When the end control valve reopens or closes the water flow at the water inlet, that is, when the pressure in the pipe is less than or equal to the critical pressure value of the spring 202, the spring 202 returns to its original state, the pressure reducing short branch pipe 100 stops flowing, and the closed water-stopping state is restored.

[0040] According to the water hammer pressure calculation formula:

[0041]

[0042] Where c is the propagation speed of water hammer wave, v is 0 is the initial flow velocity in the pipe, and v is the flow velocity in the pipe after the end control valve is closed. It can be seen that the water hammer pressure value is not only related to the wave velocity, but also proportional to the difference in flow velocity in the pipe before and after the end control valve is closed.

[0043] When there is no protection, after the control valve at the end of the pipeline is closed instantly, the flow velocity in the pipeline drops to 0, all kinetic energy is converted into pressure potential energy, and the pressure value is maximum. When the water delivery system is protected by the pressure reducing short branch pipe 100, the pipeline overpressure spring control valve 200 compresses the outflow, increases the pipeline flow velocity v after the end control valve is closed, and reduces v 0 -v item, thereby reducing the water hammer pressure in the pipeline.

[0044] The flow velocity v in the pipe after the valve is closed can be increased by increasing the area of ​​the outflow hole 201a of the outflow bottom plate 201 of the pressure reducing short branch pipe 100 or increasing the number of the pressure reducing short branch pipes 100. When the flow velocity v in the pipe is equal to the flow velocity v in the pipe before the end control valve is closed, 0 When the flow rate is consistent, the change in kinetic energy when the end control valve is instantly closed can be basically 0, and the kinetic energy converted into pressure potential energy is also basically 0, thereby achieving the purpose of reducing the water hammer pressure in the pipe, and the protection effect is the best at this time. Therefore, based on the fundamental principle of water hammer pressure generation, the present invention reduces the instantaneous water hammer pressure in the pipe by increasing the instantaneous flow rate after the control valve is closed, and effectively protects the pipeline.

[0045] Preferably, refer to Figure 4 When multiple pressure reducing short branch pipes 100 are arranged on the water transmission trunk line S, inspection valves 700 are arranged between the terminal control valve and the first pressure reducing short branch pipe 100 and between the last pressure reducing short branch pipe 100 and the upstream pipeline. By closing the upstream inspection valve 700 first and then the downstream inspection valve 700, the water flow in the pipe section where the pressure reducing short branch pipe 100 is installed can be completely drained, and all the pressure reducing short branch pipes 100 can be inspected at the same time. There is no need to arrange inspection pipe valves before and after each device like traditional protective equipment, and inspect the protective equipment one by one.

[0046] While meeting the requirements for regular maintenance of protective equipment, the above arrangement reduces the construction investment in inspection valves and inspection valve wells, the number of hydraulic fluctuations that the water supply system needs to experience due to the closing of inspection valves, and reduces the erosion of the pipe wall and hydraulic components by the high-pressure water flow in the pipe, thereby extending the service life of the pipeline.

[0047] Example 2

[0048] Reference Figure 5 , which is the second embodiment of the present invention, and is based on the previous embodiment. This embodiment provides a water hammer protection test system for verifying the beneficial effects of a water hammer protection device. The system includes a pressure sensor 400 and a water measuring weir 500.

[0049] Specifically, Figure 5This is a schematic diagram of the test layout of the protection effect of the water hammer protection test system. In order to facilitate the observation of the water flow characteristics in the pipe under different test conditions and the working decompression process of the water hammer protection test system (hereinafter referred to as the "protection system"), the test pipelines all use DN100 transparent PVC pipes with a pressure rating of 0.6MPa. The installation of the pipelines is similar to the anchoring and laying of actual pipeline projects, and nylon cable ties are used to fix the pipelines on a 60cm high steel frame.

[0050] The test system sets a control valve at the head of the pipeline, changes the test flow rate by adjusting the valve opening, and verifies the pipeline flow rate through a 500-meter water measuring weir.

[0051] A manually operated ball stop valve 600 is set at the end of the pipeline to create pipeline valve closing water hammer. The protection system is arranged on the test pipeline through the three-way joint 300, and a pressure sensor 400 (with a maximum time accuracy of 1ms) is arranged in front of the three-way joint 300 to measure the real-time pressure data of the pipeline. During the test, the water pump pumps water from the underground reservoir into the DN100 test pipeline. The water flows into the test pipeline from the head, flows out from the end of the pipeline, enters the water measuring weir 500, and finally returns to the underground reservoir through the canal to realize the circulation test system.

[0052] The test specifications of the main components of the protection system, the pressure reducing short branch pipe 100 and the spring control valve 200, are as follows: the diameter of the pressure reducing short branch pipe 100 is 100 mm and the length is 60 cm.

[0053] The outflow bottom plate 201 of the spring control valve 200 is made of an 8mm thick PVC plate cut by a high-precision engraving machine, with a diameter of 18cm. The aperture of the water outlet 201a is 4.5cm. The water outlet 201a is within the concentric circle with a diameter of 10cm. The original length of the spring 202 component is 30.8cm, the inner diameter is 70mm, the spring wire diameter is 5mm, and the stiffness coefficient is 2327N / m.

[0054] Seven groups of test conditions were set up to explore the protection performance of the protection system under different conditions, as shown in Table 1. In order to explore the change of the valve closing water hammer pressure when the number of outflow holes 201a of the outflow bottom plate 201 of the spring control valve 200 is different under the same flow rate, working conditions 1 and 2 were set up. In working conditions 1 and 2, 3 and 5 outflow holes 201a were arranged on the outflow bottom plate 201 of the spring control valve 200, respectively.

[0055] Working conditions 2 and 3 have the same pipeline flow rate and number of outflow holes 201a, but different numbers of water hammer protection devices; Working conditions 3-7 explore whether the water hammer protection devices have the same number and can effectively reduce the water hammer pressure in the pipeline when the pipeline flow rate increases, and whether their structure will be damaged by overpressure.

[0056] Among them, the flow rate in the pipe of working condition 7 reaches the burst flow rate of 49.19m3 / h when there is no protection. Under each working condition, the change process of the valve closing water hammer pressure with time when there is no protection and when the water hammer protection device is arranged is measured respectively. The spring control valve 200 is taken out from the pressure reducing short branch pipe 100. Figure 1 The test without a protection system can be completed by installing a water-retaining blind plate at the end of the short branch pipe shown in the figure instead of the original orifice plate.

[0057] Table 1 Test conditions

[0058] Working conditions <![CDATA[Flow rate m 3 / h]]> Number of water hammer protection devices Number of outlet holes 1 25 1 3 2 25 1 5 3 25 2 5 4 30 2 5 5 35 2 5 6 40 2 5 7 49.19 2 5

[0059] The measured pressure values ​​P of No. 1 and No. 2 pressure sensors when water hammer protection devices are arranged on the pipeline under various working conditions 1 , P 2 See Table 2. At the same time, the following formulas calculate the maximum pressure amplitude X of the pipeline reduced by the water hammer protection device under each working condition.

[0060]

[0061] Where P max P is the maximum water hammer pressure when the valve is closed without protection. i- is the maximum water hammer pressure collected by the pressure sensor when setting the water hammer protection device, i is 1, 2, P 1 , P 2 These are the collected values ​​of pressure sensors No. 1 and No. 2.

[0062] The test results under different working conditions are shown in Table 2. It can be seen from working conditions 1 and 2 in the table that when the number of outflow holes 201a is different under the same flow rate, the pressure rise value in the pipe caused by closing the end ball stop valve 600 decreases as the number of outflow holes 201a with the same aperture increases. The corresponding X value when the number of outflow holes 201a is 5 holes is 21.72% higher than that when the number of outflow holes 201a is 3 holes. This is because under the same water hammer pressure, the more the number of outflow holes 201a, the greater the outflow of the pressure reducing short branch pipe 100, and the more obvious the pressure reduction protection effect (the larger the X value).

[0063] At the same time, it can also be seen that the number of outflow holes 201a of the short branch pipes 1 and 2 in working conditions 3 to 7 is 5 holes, and the X values ​​calculated for the two branches under the same working condition are similar, indicating that the reduction amplitude of the water hammer pressure of the pipeline is basically the same when the specifications of the outflow holes 201a of the water hammer protection device are consistent and the outflow flow rate is the same. Therefore, the test believes that increasing the outflow area of ​​the outflow bottom plate 201 can effectively increase the protection capability of the water hammer protection device.

[0064] Table 2 Water hammer protection device protection test results

[0065]

[0066]

[0067] From the data of working conditions 2 and 3 in Table 2, it can be seen that the water hammer pressure in the pipe is the same when the end valve is closed instantaneously when the flow rate and flow velocity in the pipe are the same, but when two water hammer protection devices are arranged for joint protection in working condition 3, the water hammer pressure reduction before the end valve is 15.01% greater than that in working condition 2, indicating that the pipeline pressure reduction increases with the increase in the number of water hammer protection devices at the same flow rate. The experiment shows that increasing the number of water hammer protection devices at the same flow rate can further reduce the water hammer pressure rise value in the pipe.

[0068] From the test data of working conditions 3 to 6 in Table 2, it can be seen that the pipeline flow rate and the maximum valve closing water hammer pressure gradually increase with the increase of flow rate, and the role of the water hammer protection device in protecting the pipeline water hammer is still obvious and effective, and the maximum water hammer pressure of the pipeline can be reduced by 40.39%-66.77%. From the test results of working condition 7, it can be seen that when the flow rate reaches the most dangerous accident condition, the pipeline does not burst and maintains normal operation under the action of the water hammer protection device, indicating that the water hammer protection device can effectively protect the water hammer pressure under various working conditions.

[0069] By comparing the X values ​​of working conditions 3 to 7, it can be seen that as the maximum valve closing water hammer pressure in the pipe continues to increase, the X values ​​under the action of the two water hammer protection devices are different from P max This is because the specifications of the protective devices used in the tests under different working conditions are consistent, that is, the outflow area of ​​the bottom plate outflow hole 201a is the same, and the protective pressure reduction value remains unchanged. However, as the flow rate increases, P max So the X value increases with P max The maximum pressure in the pipe is reduced by 34.62% compared with the case without protection. The test shows that X can be increased by increasing the number of water hammer protection devices of the same specification or increasing the outflow area of ​​the outflow bottom plate of the water hammer protection device.

[0070] It can be seen from Table 2 that under each working condition, the time when the No. 2 water hammer protection device starts to flow out is later than that of the No. 1 water hammer protection device, and the maximum pressure value measured by the No. 2 pressure sensor is smaller than that of the No. 1 pressure sensor. This is because when the pressure-boosting water hammer wave generated by the terminal valve closing propagates upstream, the pressure fluctuation time at different nodes in the pipe is different. The closer to the position in front of the terminal valve, the earlier the pressure rises, and the earlier the water hammer protection device starts to work. In addition, the pressure rise value caused by the water hammer wave in the pipe gradually decreases due to energy loss during the propagation process.

[0071] Example 3

[0072] Reference Figure 6 to Figure 8 , which is the third embodiment of the present invention, and is based on the first two embodiments. This embodiment provides a simulation experiment to further verify the beneficial effects of the present invention.

[0073] Specifically, relying on the actual QT project and using the Bently HAMMER water hammer numerical simulation software, the protection effect of the water hammer protection device in the actual project and the flow velocity changes at each node of the pipeline will be further verified. The numerical simulation calculation adopts the non-steady flow mathematical model of the one-dimensional pipeline, the instantaneous friction force calculation adopts the non-steady state method, and the Hessen-William coefficient of the pipeline is set to 140. During normal operation, the end control valve is fully opened, and the characteristic line method is used to solve the basic water hammer equation under constant position head. The simulation calculation time is 2000s, and the calculation step is 0.04.

[0074] The project is located in Qitai County, Xinjiang. The water supply system consists of an upstream reservoir, pipelines, butterfly control valves, and terminal pressure regulating tanks. The total length of the water supply pipeline is 41.725 km, and the design flow rate of the main pipeline is 0.92m 3 / s, the reservoir water level is 1298.88m, the pipeline water inlet elevation is 1273.65m, the pipeline passes through piles 6+750, 18+350 and 31+300 respectively, and is connected to the 1500 cubic meter pressure regulating tank on the Zhonggegen River water diversion pipeline by three sections of DN630, DN820 and DN920, and finally merges into the Zhonggegen River water diversion pipeline network. The design water level of the pressure reducing tank is 940m, the control valve pile number is 41+276, and the terminal control valve is kept open during normal operation.

[0075] A total of 6 layout schemes were designed for numerical verification calculations. The layout schemes of water hammer protection devices and the corresponding pile number positions are shown in Table 3. The 10s linear closing of the end control valve can be used to replace the closing condition of the pipeline end control valve failure. By comparing the changes in the pressure in the pipe when there is no protection equipment and when there is a water hammer protection device, the water hammer protection capability of the water hammer protection device for the actual QT project is verified.

[0076] Table 3 Water hammer protection device verification layout plan

[0077] plan Number of protective devices Protective device arrangement pile number No protection plan 0 / Solution 1 1 41+600 Solution 2 3 41+600、41+500、41+400 Solution 3 4 41+600、41+500、41+400、41+300 Solution 4 5 41+600、41+500、41+400、41+300、41+200 Solution 5 6 41+600、41+500、41+400、41+300、41+200、41+100 Solution 6 7 41+600、41+500、41+400、41+300、41+200、41+100、41+000

[0078] During steady-state operation, the maximum pipeline pressure is 281m, which occurs at the lowest elevation of the pipeline (pile number: 13+870). Based on the maximum pipeline pressure of Scheme 1-Scheme 6, the maximum water hammer pressure of the pipeline under each scheme is calculated, and the reduction of the maximum water hammer pressure of the pipeline when different numbers of water hammer protection devices are set relative to the unprotected scheme is given, as shown in Table 4. It can be seen from the table that the maximum water hammer pressure before the valve under the unprotected scheme is 279m. After setting 1-7 protection devices, the maximum water hammer pressure drops from 202m to 2m, and the pressure reduction is 27.6%-99.28%. The water hammer pressure in the pipe under Scheme 6 is basically (99.28%) completely eliminated, indicating that the application of protection devices in actual projects can effectively reduce the water hammer pressure rise value caused by closing the valve of the water supply system.

[0079] Table 4 Water hammer protection calculation table for protective devices

[0080] plan No protection plan Solution 1 Solution 2 Solution 3 Solution 4 Solution 5 Solution 6 Maximum water hammer pressure of pipeline / m 279 202 59 43 28 15 2 Water hammer pressure reduction (%) 0 27.60 78.85 84.59 89.96 94.62 99.28

[0081] Four typical nodes J-5 (near the pipeline inlet, pile number 0+764.296), J-68 (the lowest point of the pipeline, pile number 13+870), J-91 (pile number: 23+400) and J-149 (2m before the terminal valve, pile number: 41+655) were selected on the pipeline. The pressure variation of each node with time under the unprotected scheme, scheme 1, scheme 2, scheme 4 and scheme 6 was analyzed, and the maximum pressure of the typical nodes of schemes 1, 2, 4, and 6 and the reduction of the pressure wave fluctuation time Δp / p were calculated using equations (11) and (12) respectively. 0 , Δt / t 0 , the specific results are shown in Table 5.

[0082]

[0083] In the formula, p max is the maximum water hammer pressure at the node under each scheme, p 0 is the maximum water hammer pressure at the node under the unprotected scheme, t 2 is the time when the node pressure starts to fluctuate under each scheme, t 1 is the time for node pressure to stop fluctuating under each scheme, t 0 It is the node pressure fluctuation duration under the unprotected scheme.

[0084] It can be seen from the table that from the node at the head of the pipeline to the node at the end of the pipeline, the pressure values ​​are attenuated to varying degrees when different numbers of water hammer protection devices are set. The water hammer pressure values ​​along the pipeline are greatly reduced, and the fluctuation duration is significantly reduced.

[0085] The sum of each node increases in schemes 1, 2, 4, and 6, and the reduction corresponding to scheme 6 is the largest, with each node being 93.68%, 100%, 99.49%, 98.58%, 94.03%, 93.23%, 91.64%, and 90.70%. This is because the number of protective devices increases, the outflow of the short branch increases, and the water hammer wave reflected back to the front of the terminal valve is discharged from the water supply system along with the outflow of the short branch, which effectively reduces the water hammer pressure rise value and reduces the pressure in the pipe. It shows that the role of the protective device in reducing the amplitude of node pressure fluctuation and shortening the duration of node pressure fluctuation increases with the increase of the number of protective devices. The protective effect of the protective device is positively correlated with the number of protective devices arranged in the pipeline. When the branch pipe diameter is constant and the total flow of the branch pipe is equal to the main flow before closing the valve, the number of branches is optimal.

[0086] Table 5 Calculation table of positive water hammer pressure and pressure fluctuation duration at typical nodes

[0087]

[0088] Calculate t for each solution separately 1 =L / c(t=46.9s) and t 2 =2L / c (t=93.8s) when the pipeline flow rate is simulated and set from the upstream reservoir to the terminal control valve as the positive direction. Figure 7 It can be seen that t 1 In the absence of a protection scheme at all times, the flow velocity before the terminal valve is 0, and the pipeline flow velocity gradually decreases from before the terminal valve. The pipeline flow velocity in the range of pile numbers 18+984-41+725 (i.e., x is 1.89-4.17 in the figure) is close to 0m / s.

[0089] The velocity in the same section under schemes 1, 2, 4, and 6 is not 0, and the velocity gradually increases. The velocity intervals in the same pipeline range under each scheme are [0.28, 0.44], [0.4, 0.75], [0.51, 1.04], and [0.66, 1.29], respectively. This shows that the water hammer protection device effectively increases the flow velocity in the pipe after the end valve is closed. As the number of protection systems increases, the flow velocity in the pipeline also increases after the control valve is closed. Figure 8 It can be seen that t 2 The pipeline flow rate under the unprotected scheme is always negative and the flow rate is fast, indicating that there is a high-speed water flow in the pipe from the terminal control valve to the upstream reservoir. The pipeline flow rate under schemes 1, 2, 4, and 6 is positive, and the flow rate range of the entire pipeline under each scheme is [0.14, 0.48], [0.17, 1.99], [0.2, 2.76], and [0.3, 2.87], respectively. This shows that the water flow in the pipe keeps flowing from the upstream reservoir to the terminal control valve, and the flow rate gradually increases. Because the number of protective devices gradually increases, the total outflow of the drain valve increases, which increases the flow rate after the valve is closed in the pipe, effectively eliminating the reverse flow of water in the pipe caused by the closure of the terminal control valve.

[0090] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A water hammer protection device suitable for a pipeline containing silt, characterized in that: include, A pressure reducing short branch pipe (100), at least one of which is arranged along the water supply main pipe (S) and one end of which is connected to the water supply main pipe (S); A spring control valve (200) is arranged at the other end of the pressure reducing short branch pipe (100); when a water hammer effect occurs in the water supply main pipe (S), an overpressure water flow will flow out from the end of the pressure reducing short branch pipe (100) through the spring control valve (200).

2. The water hammer protection device suitable for a pipe containing sediment as claimed in claim 1, characterized in that: The pressure reducing short branch pipe (100) is connected to the water supply main pipe (S) via a three-way joint (300).

3. The water hammer protection device suitable for a pipe containing sediment as claimed in claim 2, characterized in that: The diameter of the pressure reducing short branch pipe (100) is 1 / 5 to 1 / 3 of the diameter of the water supply main pipe (S).

4. The water hammer protection device suitable for a pipe containing silt as claimed in claim 3, characterized in that: The spring control valve (200) comprises an outflow bottom plate (201), a spring (202) and a waterproof plug (203); the outflow bottom plate (201) and the waterproof plug (203) are respectively fixedly arranged at two ends of the spring (202) and the three are coaxial.

5. The water hammer protection device suitable for a pipeline containing silt as claimed in claim 4, characterized in that: At least one outflow hole (201a) is provided on the outflow bottom plate (201) for connecting the pressure reducing short branch pipe (100) with the outside.

6. The water hammer protection device suitable for a pipeline containing sediment as claimed in claim 5, characterized in that: The sides of the outflow bottom plate (201) and the waterproof plug (203) are both fixedly provided with fixed steel sheets (204), and the two ends of the spring (202) are respectively fixedly connected to the fixed steel sheets (204).

7. The water hammer protection device suitable for a pipeline containing sediment as claimed in claim 6, characterized in that: A pull rope (205) is also provided between the outflow bottom plate (201) and the waterproof plug (203), and two ends of the pull rope (205) are respectively fixedly connected to the outflow bottom plate (201) and the waterproof plug (203).

8. The water hammer protection device suitable for a pipeline containing sediment as claimed in claim 7, characterized in that: The pull rope (205) pre-applies tension to the spring (202), so that the spring (202) is compressed and pulled. The pressure of the spring (202) at this time is the same as the water pressure in the pressure reducing short branch pipe (100) when no water hammer occurs.

9. A water hammer protection test system, characterized in that: The water hammer protection device according to any one of claims 1 to 8 further comprises: A pressure sensor (400) is arranged upstream of the water hammer protection device and is used to measure the water pressure in the water main (S); A water measuring weir (500) is arranged at the water outlet of the water main pipe (S) and is used to check the flow rate of the water main pipe (S).

10. The water hammer protection test system according to claim 9, characterized in that: The water measuring weir (500) is a triangular water measuring weir, and a spherical stop valve (600) is also provided at the water delivery main pipe (S).

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